title: Urinary bromotyrosine measures asthma control and predicts asthma exacerbations in children.
abstract: OBJECTIVE
  To determine the usefulness of urinary bromotyrosine, a noninvasive marker of eosinophil-catalyzed protein oxidation, in tracking with indexes of asthma control and in predicting future asthma exacerbations in children.
  
  
  METHODS
  Children with asthma were recruited consecutively at the time of clinic visit. Urine was obtained, along with spirometry, exhaled nitric oxide, and Asthma Control Questionnaire data. Follow-up phone calls were made 6 weeks after enrollment.
  
  
  RESULTS
  Fifty-seven participants were enrolled. Urinary bromotyrosine levels tracked significantly with indexes of asthma control as assessed by Asthma Control Questionnaire scores at baseline (R = 0.38, P = .004) and follow-up (R = 0.39, P = .008). Participants with high baseline levels of bromotyrosine were 18.1-fold (95% CI 2.1-153.1, P = .0004) more likely to have inadequately controlled asthma and 4.0-fold more likely (95% CI 1.1-14.7, P = .03) to have an asthma exacerbation (unexpected emergency department visit; doctor's appointment or phone call; oral or parenteral corticosteroid burst; acute asthma-related respiratory symptoms) over the ensuing 6 weeks. Exhaled nitric oxide levels did not track with Asthma Control Questionnaire data; and immunoglobulin E, eosinophil count, spirometry, and exhaled nitric oxide levels failed to predict asthma exacerbations.
  
  
  CONCLUSIONS
  Urinary bromotyrosine tracks with asthma control and predicts the risk of future asthma exacerbations in children.
authors.affiliation: Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44195, USA.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Wedes
authors.forename: Weijia
authors.initials: W
authors.lastname: Wu
authors.forename: Suzy A A
authors.initials: SA
authors.lastname: Comhair
authors.forename: Karen M
authors.initials: KM
authors.lastname: McDowell
authors.forename: Joseph A
authors.initials: JA
authors.lastname: DiDonato
authors.forename: Serpil C
authors.initials: SC
authors.lastname: Erzurum
authors.forename: Stanley L
authors.initials: SL
authors.lastname: Hazen
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000503:physiopathology / Q000652:urine*; D015415:Biomarkers / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005500:Follow-Up Studies; D005540:Forced Expiratory Flow Rates; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012008:Recurrence; D013147:Spirometry; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000652:urine; D055815:Young Adult
chemical_list: D015415:Biomarkers; C475724:bromotyrosine; D014443:Tyrosine